Excuse my ignorance....whats a Crutchfield Master Sheet?

Crutchfield is a mail-order car stereo merchant in the US. They are very popular. The master sheet is something they send you that tells you how to install a stereo in your specific car. They are pretty good guides on how to take your dash apart and what tools you need. You get the MasterSheet for free when you buy a stereo from them (usually at list price). You can also just buy the MasterSheet here for $5.